Installing

There are a number of language packs available for Firefox, other than the standard English. Language packs are usually named as firefox-i18n-languagecode (where languagecode can be any language code, such as de, ja, fr, etc.). For a list of available language packs see this.

Add-ons

Firefox is well known for its large library of add-ons which can be used to add new features or modify the behavior of existing features of Firefox. You can find new add-ons or manage installed add-ons with Firefox's "Add-ons Manager."

GNOME Keyring integration

KDE integration

To use KDE's KPart technology with Firefox, by embedding different KDE file viewers into the browser, you can install kpartsplugin.

To get further integration with KDE's Oxygen theme, you can install Oxygen KDE, a very comprehensive theme that also has color scheme detection, support for Firefox's Persona themes, support for both the Oxygen and Faenza icons and various other customizations.

For integration with KDE’s mime type system and file dialogs, one can use a version of firefox with OpenSUSE’s patches applied.

Dictionaries for spell checking

To enable spell checking for a specific language right click on any text field and check the Check Spelling box. To select a language for spell checking to you have right click again and select your language from the Languages sub-menu.

To get more languages just click Add Dictionaries... and select the dictionary you want to install from the list.

Troubleshooting

Setting your e-mail client

Firefox is usually set to open mailto links with a web application such as Gmail or Yahoo Mail. To set your e-mail client in Firefox to use with mailto links, go to Preferences > Applications and modify the action column corresponding to the mailto content type. You have set this to the exact location of your e-mail client (e.g. /usr/bin/kmail for Kmail).

Firefox 4 New Menu Bar/Firefox Button

This article or section is a candidate for merging with Firefox Tweaks.

Notes: This is just style tweaks, should better keep it in tweak page to keep main page clean. (Discuss in Talk:Firefox#)

To toggle between the new Firefox button and the classic menu bar:

if the button is active, check Preferences > Menu Bar, or right click in the toolbar area and check Menu Bar.

if the menu bar is active, uncheck View > Toolbars > Menu Bar, or right click in the toolbar area and uncheck Menu Bar.

In GNU/Linux, you will just get a plain grey button instead of the new orange one from Windows. However you can change this to either a Firefox icon or the icon followed by the "Firefox" text.

Adding the following to your ~/.mozilla/firefox/userprofile/chrome/userChrome.css file will place the icon before the text:

Make plugins respect blocked pop-ups

Some plugins can misbehave and bypass the default settings, such as the Flash plugin. You can prevent this by doing the following:

Type about:config into the address bar.

Right-click on the page and select New and then Integer.

Name it privacy.popups.disable_from_plugins.

Set the value to 2.

The possible values are:

0: Allow all popups from plugins.

1: Allow popups, but limit them to dom.popup_maximum.

2: Block popups from plugins.

3: Block popups from plugins, even on whitelisted sites.

Middle-click errors

A common error message you can get while using the middle mouse button in Firefox is:

The URL is not valid and cannot be loaded.

Another symptom is that middle-clicking results in unexpected behavior, like accessing a random web page.

The reason stems from the use of the middle mouse buttons in UNIX-like operating systems. The middle mouse button is used to paste whatever text has been highlighted/added to the clipboard. Then there is the possibly conflicting feature in Firefox, which defaults to loading the URL of the corresponding text when the button is depressed. This can be easily disabled by going to about:config and setting the middlemouse.contentLoadURL option to false.

Alternatively, having the traditional scroll cursor on middle-click (default behavior on Windows browsers) can be achieved by searching for general.autoScroll and setting it to true.

Backspace does not work as the 'Back' button

As per this article, the feature has been removed in order to fix a bug. To re-introduce the original behavior go to about:config and set the browser.backspace_action option to 0 (zero).

Firefox does not remember login information

It may be due to a corrupted cookies.sqlite file in Firefox's profile folder. In order to fix this, just rename or remove cookie.sqlite while Firefox is not running.

Open a terminal of choice and type the following:

$ cd ~/.mozilla/firefox/xxxxxxxx.default/
$ rm -f cookies.sqlite

Note: xxxxxxxx represents a random string of 8 characters.

Restart Firefox and see if it solved the problem.

Unreadable input fields with dark GTK+ themes

When using a dark GTK+ theme, one might encounter Internet pages with unreadable input and text fields (e.g. Amazon can have white text on white background). This can happen because the site only sets either background or text color, and Firefox takes the other one from the theme.

A work around is to explicitly setting standard colors for all web pages in ~/.mozilla/firefox/xxxxxxxx.default/chrome/userContent.css.

The following sets input fields to standard black text / white background; both can be overridden by the displayed site, so that colors are seen as intended:

"Do you want Firefox to save your tabs for the next time it starts?" dialog does not appear

Firefox uses ugly fonts for its interface

If the fonts in the menu bar look ugly to you, chances are you're missing better looking fonts for Firefox to use. As a quick remedy, just install Type 1 fonts from the xorg-fonts-type1 package, available in the official repositories.

Firefox uses ugly fonts on certain webpages

When Firefox uses bitmap fonts, it can happen that on certain webpages the fonts are very ugly (compared to Google Chrome for example):